JPS6137077A - Method for rapid cooling of bean curd and apparatus therefor - Google Patents

Abstract

PURPOSE:To obtain bean curd having good preservation quality without growth of bacteria, by washing and cooling bean curd obtained in a process ranging from the raw material treatment to product cutting still at a high temperature in water, directly packaging the bean curd, and rapidly cooling the packaged bean curd in cooling water kept at ice temperature. CONSTITUTION:Bean curd obtained in a process ranging from raw material treatment to product cutting still at a high temperatured (about 80 deg.C) is washed with water in a short time and cooled. The bean curd is then taken out of a washing tank, directly packaged at a high temperature (about 50 deg.C) and then transferred from a charging inlet 13 of a cooling water tank 1 to a conveyor 10, dipped in cooling water kept at about ice temperature and rapidly cooled to a given temperature (about 5-6 deg.C).

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a rapid cooling method for producing tofu, particularly cut tofu, and an apparatus used therefor.

[Conventional technology]

To make cut tofu, the raw materials are washed, soy milk is obtained through soaking, grinding, steaming, and dispersion processes, which is coagulated and cut into a predetermined size, then exposed and cooled in a water tank for 1 to 2 hours. Currently, the products are packaged, kept at a predetermined temperature in cold water or in a refrigerator, and then shipped.

The general manufacturing process of cut tofu and the operating conditions in each process are as follows.

Raw materials - Washing - Soaking - Grinding - Steaming (100°C) - Separation - Soybean milk - Coagulation (product temperature is 80-70°C) - Product cutting - Exposing and cooling (cooling water tank with water temperature maintained at 15-20°C) ) - Packaging - Refrigerator (2 hours) to lower the temperature of the tofu from 80 to 70°C to 20 to 15°C.
Store the tofu at 0-15℃ in the refrigerator for 10-12 hours.
Lower the temperature of the tofu to 5-7℃. ) - Shipping.

However, the tofu manufacturing process uses a large amount of water, and cooling water in particular accounts for 20 to 30% of that water, so cooling costs such as water, sewage, and electricity cannot be ignored. It is something that cannot be done.

However, despite using such a large amount of water and cooling with cooling water, bacteria tend to adhere to and multiply on tofu during the manufacturing process, causing problems such as spoilage and deterioration of taste. Another drawback is that the flavor of tofu is washed away by the large amount of water used during the cooling process.

[Problem that the invention seeks to solve]

The biggest problem with the conventional tofu manufacturing process mentioned above is the process after cutting the product, which takes more than half a day.In particular, the long time between exposure, cooling, and packaging can lead to bacterial growth. A major problem is that there is a lot of falling and adhesion, and in addition, the propagation of bacteria is promoted during the subsequent cooling for a long time in the refrigerator (3).Also, since these processes take a long time, the cooling Rising costs for water, electricity, and other items are also a problem.

[Means for solving problems]

In view of the above-mentioned current situation, this invention has been developed to produce tofu produced and cut by a conventional method, that is, tofu that is still at a high temperature (80%
The tofu is exposed and cooled in water for a short time, then immediately packaged, and then introduced into a cooling device containing cold water maintained at approximately ice temperature and rapidly cooled by continuous movement. The so-obtained tofu is free from bacterial growth and can be shipped on the same day without the need for long-term cooling in a refrigerator as in the conventional method.

The steps and operating conditions in the method of this invention are shown below, following the example of the conventional method.

Raw materials = (This is the same as the conventional method, so the description is omitted) - Product cutting - Sarasaku in a water tank with a water temperature of 17 - 20°C for 8 -
(Exposed for 10 minutes and cooled the tofu temperature from 80°C to 50°C) - Packaging - Cooling (Soaked in a cooling water bath maintained close to ice temperature for 40-45 minutes and cooled from 50°C to 5-6°C) - Shipping/Storage (refrigerator) □ Shipping This is the cooling step in the above process. In this invention, a cooling mechanism having a heat storage function using ice is incorporated as a cooling device used for cooling the tofu, and preferably an ice thickness sensor. The system automatically stores the energy contained in the ice and maintains the temperature of the cold water inside at ice temperature, that is, close to 0°C, for rapid cooling.

More specifically, in the past, a simple water cooler was used to cool tofu, and this utilized the sensible heat of the cooling water, but in this invention, the cooling of ice, which has a large amount of heat of fusion, is The aim is to effectively use the latent heat of time to cool tofu, and the large amount of latent heat of ice when it melts is taken in according to the cooling load, and sensible heat and latent heat are used at the same time to achieve a synergistic effect. It is intended to be cooled by

The cooling device used in this case will be described below with reference to the drawings.

That is, FIG. 1 is a plan view of the cooling device according to the present invention, and FIG. 2 is a cross-sectional view taken along line A--A in FIG. 1. 1 and 2, 1 indicates a cooling water tank, and inside this cooling water tank 1, a cold water discharge pipe 3, a heat storage cooling pipe 2, and a tofu transfer conveyor 10 are superimposed from the bottom to the top. It is provided.

The cold water discharge pipe 3 is provided with a large number of cold water discharge nozzles on the pipe wall, and the cold water in the cooling water tank 1 is circulated through the circulation pump 5, and if desired, air is supplied and discharged together. By stirring and mixing the water in 1, the water temperature is made uniform and the cooling effect is enhanced.

The heat storage cooling pipe 2 passes refrigerant from the refrigerator into the pipe to form ice of a predetermined thickness on the pipe surface, and melts the ice with cold water from the cold water discharge pipe 3 to maintain the inside of the cooling water tank 1 at a constant ice temperature ( 0℃
).

The tofu transfer conveyor 10 moves from one end of the cooling water tank 1 to the other end, and transports the packaged tofu 12 to be input from the input side 3 at one end toward the other end, and from the output side 14 at the other end to the cooling water tank 1. It can be taken out continuously.

Note that 6 is a cold water inlet, 7 is a cold water outlet, 8 is a refrigerant inlet, and 9 is a cold water inlet.
is a refrigerant outlet, and 11 is a water tank water surface.

[For production]

Now, the high-temperature (approximately 50°C) tofu that has been taken out of the bleaching water tank (not shown) in the bleaching process and packaged is put into the cooling water tank 1 from the tofu input side 13 of the cooling water tank 1, and is placed in the upper part of the cooling water tank 1. The installed conveyor 10 is placed on it and immersed in cold water maintained at approximately ice temperature, and the cooling water tank 1
Heat is efficiently removed by contact with the cold water inside the container, and the product is rapidly cooled to a predetermined temperature (approximately 5 to 6°C), and then either stored in a case and shipped immediately, or temporarily stored in a refrigerator. It is to be kept.

Here, the heat storage cooling pipe 2 installed in the cooling water tank 1 collects ice with an amount of heat equivalent to 25 to 30% of the cooling load required for the total daily production by detecting it with an ice thickness sensor during the machine's down time such as at night. By automatically storing heat and always keeping the water temperature in the cooling water tank 1 at an ice temperature close to 0℃, and by effectively using the cooling capacity of the refrigerator and the latent heat of melting a large amount of ice during operation, it is especially possible to improve production. Cooling can be performed stably and in a short time even during peak load fluctuations.

〔Example〕

This invention will be described below with reference to Examples and Reference Examples.

Example 1 Tofu (cotton and silk) produced according to a conventional method at a temperature of 80°C was exposed for 8 minutes in a water tank maintained at a water temperature of 17°C and cooled, then taken out from the water tank and individually packaged.

This packaged tofu was placed in the cooling water tank 1 shown in FIGS. 1 and 2, and rapidly cooled under the conditions shown in Table 1 below.

As is clear from Table 1, the tofu was rapidly cooled in a short period of time and was ready for immediate shipment.

Margin below Note that in the above example, the amount of cooling water consumed in the exposing and cooling steps of tofu production is approximately 40% of the amount of cooling water used in the conventional method, resulting in a 60% savings. It was the amount of water.

Reference Example 1 Various types of bacterial growth over time for firm tofu produced according to Example 1, packaged and cooled (referred to as the product of this invention) and firm tofu produced conventionally and cooled and packaged (referred to as the conventional product) We investigated the propagation tendency. The results were as shown in Table 2.

Notes in the margins below: 1) In Table 2 above, samples A and B are products with different manufacturing dates and inspection dates, respectively.

Note 2) Storage temperature is 5℃.

〔Effect of the invention〕

This invention involves cutting tofu produced by a conventional method and immediately packaging it in a high temperature state after a short exposure and cooling process, and then rapidly cooling it in a cooling device having the specific function described above. However, this can bring about many excellent effects listed below.

(11 Because the time it takes to package cut tofu is extremely short, there are few bacteria falling into the air, and because it passes through the temperature range for viable bacteria growth in a short period of time and is cooled to a temperature that inhibits the growth of viable bacteria, The proliferation of viable bacteria is inhibited to a large extent, resulting in high-quality tofu that has a long shelf life.

(2) Temporary exposure/cooling for packaging and full-scale cooling are separate processes, and the tofu is rapidly cooled in a short period of time, so the working time can be greatly shortened.

(3) Because the temporary exposure and cooling time is short, only the scum of the tofu is removed and the flavor of the tofu remains.

(4) Since tofu is packed while still hot, it is flexible and less likely to break.

(5) Because assembly work can be performed, the product can be shipped in as little as two hours after the start of work.

(6) In the cooling device, tofu packaged at high temperature can be stably cooled in a short time by maintaining the amount of heat stored in the ice under set conditions and performing cooling that is effective simultaneously with the capacity of the refrigerator.

(7) The water temperature in the cooling device is always maintained at an ice temperature close to 0°C, which, together with the movement of tofu into the tank after packaging, reduces water contamination, reduces the need to replace cold water, and significantly reduces the amount of water used and wastewater discharged. Side limits are possible.

[Brief explanation of the drawing]

FIG. 1 is a central vertical cross-sectional view of the rapid cooling device according to the invention, and FIG. 2 is a cross-sectional view taken along line A--A in FIG. 1. ■...Cooling water tank 2...Heat storage cooling pipe 3...Cold water discharge pipe 5...Circulation pump 10...Transfer conveyor patent Applicant: Toyo Co., Ltd. Procedural amendment September 1980 7 and day

Claims (2)

[Claims] (1) Cut tofu produced by a conventional method is exposed to a water tank for a short period of time to cool it, and the still-hot tofu is packaged, and then the packaged tofu is kept at almost ice temperature using a heat storage function in cold water. 1. A method for rapidly cooling tofu, which comprises introducing the tofu into a cooling device in which the tofu exists and rapidly cooling it while continuously moving the tofu in the cooling device. (2) From the bottom to the top of the device, place a cold water discharge pipe with a large number of discharge holes, a heat storage cooling pipe, and tofu packaged in a high temperature state so that they flow continuously from one end of the device to the other. A rapid cooling device for tofu, which sequentially incorporates a tofu transfer mechanism that can be moved and taken out to the outside, and maintains the internal cold water at approximately ice temperature using the cold water discharge pipe and the heat storage cooling pipe.